Nonmelting-flesh trait in peaches is not related to low ethylene production rates

The notion that ethylene production levels in nonmelting-flesh (NMF) peach (Prunus persica L.) fruit are normally lower than those in melting-flesh (M F) fruit is refuted in our study. In fact, NMF fruit ('Oro A' and FL 86-28C ) usually produced higher levels of ethylene than did MF fruit (FL 90-20 an d 'TropicBeanty'). In both MF and NMF peaches, the rate of ethylene product ion, rather than the respiration rate, provided a good indication of the de velopmental stage of the fruit at harvest. Ethylene content in fruit on the tree followed a climacteric pattern, with the level in 'Oro A' (NMF) and F L 90-20 (MF) peaking at 50 and 12 mu L.L-1, respectively. The respiratory c limacteric was not apparent in either 'Oro A' or FL 90-20, and levels of CO 2 were similar in both genotypes.